9.2.1 and Eudora 5.1 seem okay on my end...
Just a shot in the dark, but you may try-
1. Is the Eudora Settings file in the Eudora Folder, in the Documents Folder? Mine got lost a while back, when I upgraded my hard drive, and I had to find it amongst my backups.
2. Rebuild the desktop? (Restart, hold down option + command keys until you get the "rebuild desktop?" prompt)
Anybody else got any big ideas?